The London Sun is trying to sell that the erstwhile "Home Alone" star, 29, who became friends with the King of Pop in the early '90s, is the so-called "mystery dad" of his youngest son, 7-year-old Prince Michael II, better known as Blanket.
"Jackson and Culkin were best friends," a source tells the tab. "He was one of the few people Jackson really trusted and Mack never let him down. Really, Jackson idolized him -- that's why he asked Mack to donate sperm. Deep down, I think he always wished Mack was his son. Creating Blanket was the next best thing."
Try to keep your eyes from rolling out of your head, because the snitch, who fails to offer any insight into the enigma surrounding Blanket's maternal origins, isn't done.
"This isn't just chitter-chatter," adds the mole. "Even Culkin suspects he's Blanket's father."
That appears to be news to Macaulay, whose rep responded to our request for comment by saying the entire matter is "too preposterous for us to even acknowledge."
Culkin testified on Jackson's behalf in his 2005 molestation trial, denouncing the allegations against him as "absolutely ridiculous" and describing his numerous stays at Neverland Ranch as completely innocent.
"We would play video games, fill up water balloons and just have good old fun," he said. "We were kids having a good time."
Speaking of kids, the rumor mill continues to churn over Jackson's two older kids, Prince Michael, 12, and Paris, 11, with both his dermatologist, Arnold Klein, and onetime child star Mark "Oliver!" Lester dropping hints about a possible DNA connection.